R/watermark.R

In davebraze/FDBpub: Helpers for report writing

##' @title Watermark ggplot with "DRAFT"
##'
##' @description Watermark ggplot with "DRAFT" or other text.
##'
##' @details Watermark ggplot with "DRAFT" or other text.
##'
##' @param plot A ggplot object to be watermarked.
##' @param label Text to use as watermark. Defaults to "DRAFT".
##' @param size Text size in points. Defaults to 108.
##' @param color Watermark color. Defaults to "black".
##' @param alpha Watermark transparency. Defaults to 0.1.
##' @param angle Watermark angle. Defaults to 45°.
##' @param x x position of label. Defaults to 0.5.
##' @param y y position of label. Defaults to 0.5.
##' @param do logical specifying whether to apply the watermark. Defaults to TRUE.
##' @param ... Arguments passed to cowplot::draw_label()
##' @importFrom cowplot ggdraw draw_label
##' @export
##' @return A ggplot2 object.
##' @author Dave Braze \email{davebraze@@gmail.com}
##' @seealso \code{\link[cowplot]{draw_label}}
##' @examples
##' library(ggplot2)
##' data(iris)
##' tmp <- ggplot(iris, aes(x=Sepal.Length, y=Sepal.Width, color=Species)) +
##'   geom_point()
##'   watermark(tmp)
##'
##' ## alternately, in an rmarkdown file maybe do
##'
##' watermark(tmp, do=is_draft())
##'

watermark <- function(plot,
                      label="DRAFT",
                      size=108,
                      color="black",
                      alpha=0.1,
                      angle=45,
                      x = 0.5,
                      y = 0.5,
                      do = TRUE,
                      ...)
{
    if(!do) return(plot)

    ggdraw(plot) +
        draw_label(label = label,
                   size = size,
                   color = color,
                   alpha = alpha,
                   angle = angle,
                   x=x, y=y,
                   ...)

}